Waterborne coating products typically contain water and organic compounds at a level that makes them susceptible to microbial growth. Contamination by bacteria, yeast, or mold can occur during manufacturing or during use by the consumer. Contaminating microbes introduced at the time of manufacture have considerable time to grow during storage and transport, on the shelf at the point of sale, and before use. During use, contamination can occur due to contact of the coating product with tools, secondary containers, and users.
Antimicrobial agents are typically added to waterborne coatings or coatings ingredients to limit the growth of bacteria, yeast, or mold in the product. There are a very limited number of antimicrobial chemistries available for this purpose. The type of antimicrobial agent or combination of agents (i.e., antimicrobial system), and their concentration in the product, is selected based on the type of product being preserved, the efficacy of the agent, and the types of organisms that are likely to contaminate the product. The antimicrobial systems are further limited to concentrations below which they are deemed safe for use based on environmental or heath concerns. Some agents are known to cause skin sensitization in susceptible individuals and are therefore limited in concentration by government regulation.
Glycols have been identified as having antimicrobial activity such that when used at efficacious concentrations in coatings and various other products, the glycol can augment or enhance the antimicrobial system used. Such glycols include propylene glycol, dipropylene glycol, tripropylene glycol, and 1,3-butylene glycol.
There is a need in the art for additional, more effective antimicrobial agents and systems for use in coating compositions and aqueous dispersions. The present invention is directed to solving this need as well as others that will be apparent from the following description and claims.